1. Field of the Invention
The present invention relates generally to an optical lens having a fluorescent layer, which is adapted for being employed in an LED packaging structure, and more particularly, to an optical lens employed in an LED packaging structure, in that the optical lens includes a fluorescent layer buried inside the optical lens and facilitates heat dissipation, and provides a light mixing and guiding function.
2. The Prior Arts
LEDs are known as solid state semiconductor devices. When electrical current flows through a semiconductor PN junction of an LED, the energy carried by two kinds of carriers are converted into a light form and released thereby. LEDs typically have the advantages including light weight, fast responding speed, and high efficiency, and are thus widely applied in a variety of industries.
Referring to FIG. 1, it is a cross-sectional view of a conventional multi-layer LED packaging structure. The multi-layer LED packaging structure includes a substrate 10, a molded platform 12, a lead frame 14, and a mantle 16. The substrate 10 is positioned at the bottom, and the molded platform 12 is adapted for integrating the substrate 10 with the lead frame 14. A plurality of LED dice 18 are arranged in an array form on the substrate 10. The substrate 10 is made of a metal material. The LED dice 18 are electrically connected with the lead frame 14. The mantle 16 and the molded platform 12 are correspondingly coupled to define a sealed inner space. An insulation protection layer 20 is formed covering the LED dice 18. A fluorescent layer 22 is formed on the insulation protection layer 20.
However, the fluorescent layer 22 disposed over the LED dice 18 is directly illuminated by the light emitted from the LED dice 18, and directly absorbs heat generated by the LED dice 18 when emitting light. Unfortunately, ordinary fluorescent layer is usually featured with a low heat-resistance temperature and a poor thermostability. When the heat generated by the LED dice 18 is transmitted to the fluorescent layer 22, the fluorescent layer 22 might be degraded with a lowered light emitting efficiency and an affected photochromism. Further, the fluorescent layer 22 is usually configured on the LED dice 18 by an injection process or a coating process, which requires using excessive fluorescent material for assuring that all of the LED dice 18 are uniformly covered by the fluorescent layer 18. However, such a method unavoidably wastes raw materials. Further, if the fluorescent layer is defective, the LED dice 18 cannot be recycled for reuse. Moreover, according to the conventional technology, optical tests can be conducted only after the fluorescent layer processing. As such, it is desired to provide an LED packaging structure for solving all of the foregoing shortcomings.